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  • 1
    Electronic Resource
    Electronic Resource
    Transmission electron microscopy study of microstructure and misfit dislocations in epitaxial LiTaO3 thin films grown on sapphire by a metalorganic chemical vapor deposition process (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 3675-3680 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Epitaxial lithium tantalate thin films were grown on the prismatic plane of sapphire substrates by metalorganic chemical vapor deposition. The film contained two crystallographic variants, both epitaxially oriented with respect to the substrate. The variants were related to each other by 180° rotation about the c axis (which lies in the interface plane). A rectangular misfit dislocation network at the interface was imaged by cross-sectional high-resolution transmission electron microscopy, along two orthogonal directions, and by plan-view weak beam dark field transmission electron microscopy. The Burgers vectors of these two orthogonal sets of misfit dislocations were determined to be 1/3[11¯00] and 1/3[0001]. The spacing of the dislocations was nearly exactly equal to the ideal values suggesting a very high degree of epitaxy, which was also confirmed by nearly equal values of the full width at half-maximum of x-ray peaks in the ω scans obtained from the overgrowth and the sapphire substrate. The perfection of the epitaxy is attributed to the lack of multiplicity of slip systems in the interface plane for accommodating the misfit. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361197
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  • 2
    Electronic Resource
    Electronic Resource
    Observation of body centered cubic Cu in Cu/Nb nanolayered composites (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 2103-2105 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The deposition of thin alternating layers of Cu and Nb on Si(100) substrates has been studied by transmission electron microscopy as a function of layer thickness. For layer thickness above 25 Å, there is a strong texture orientation relationship with the close packed planes of fcc Cu parallel to close packed planes of bcc Nb, forming the so-called "Kurdjumov-Sachs" orientation relationship. However, at thicknesses of under 12 Å, the Cu is constrained to grow as a slightly distorted bcc structure. It is thought that, when it reaches a critical thickness between 12 and 20 Å, the bcc Cu loses coherency and transforms martensitically to the fcc phase, resulting in the observed Kurdjumov–Sachs orientation relationship. Electron energy loss spectroscopy observations indicate a difference of 2 eV in the L3 edge suggesting that the Fermi energy is lower in the constrained bcc form of Cu than in the equilibrium fcc structure. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.119611
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  • 3
    Electronic Resource
    Electronic Resource
    Determination of crystallographic polarity of CdTe crystals with Auger electron spectroscopy (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 924-927 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The crystallographic polarity of CdTe crystals has been studied with Auger electron spectroscopy. The polarity of various surfaces could be determined by normalizing the low-energy Te (NOO) peak with the high-energy Te (MNN) peak. Upon comparing the normalized ratios from both {111} surfaces, the ratio from (111) Te surfaces was found to be about 1.3 times that from (111) Cd surfaces. The identified polarity was consistent with recent results of anomalous absorption of x rays, the convergent beam method of transmission electron microscopy, and chemical etching. Air-cleaved {110} surfaces of CdTe crystals and surfaces of pure Te crystals were studied for comparison as well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.338143
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  • 4
    Electronic Resource
    Electronic Resource
    Etching on polar (111) surfaces of CdTe crystals studied with Auger electron spectroscopy (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 4453-4459 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Various reducing and oxidizing etches were applied to the polar (111)Cd and (111)Te surfaces of CdTe crystals. The induced surface layers were studied with Auger electron spectroscopy, and the chemical reactions involved were discussed. A dithionite etch left both (111) Cd and (111)Te surfaces Cd rich. The sulfur in the etch solution appeared to replace Te in the near surface. A hydrazine etch left the Cd to Te ratio about one to one on the surfaces. A large oxygen peak was observed to increase as the etching time and temperature increased, indicating that the etch was not reducing. Hydrogen heat treatment left the surface stoichiometric, free of contamination and crystalline. Hydrogen heat treatment was the best method we have tried to retain the stoichiometry of the (111)CdTe surfaces. The surfaces treated with oxidizing EAg-1 solution were Te rich, and the strong correlation between the relative concentration of Te and Ag suggested a reaction between Te and Ag. The Te(NOO)/Te(MNN) ratio on (111)Te surfaces was always significantly higher than that on (111)Cd surfaces after hydrogen heat treatment or sputter cleaning consistent with the crystallographic polarity we reported previously.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339033
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  • 5
    Electronic Resource
    Electronic Resource
    Spiral growth of GaAs by metalorganic vapor phase epitaxy (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 1959-1961 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Growth spirals are observed on metalorganic vapor phase epitaxy grown GaAs surfaces by atomic force microscopy. The growth mechanism is according to the classical Burton–Cabrera–Frank theory. Spirals originate from screw dislocations. Successive turns of steps are sent out by the dislocations. These steps are of monolayer height (0.28 nm) and the interstep distance is around 150 nm. The spiral steps are well developed around the screw dislocations, while the adjacent vicinal steps lack the regularity of the spiral steps. Two-dimensional nucleation islands are also observed on the vicinal steps.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.111755
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  • 6
    Electronic Resource
    Electronic Resource
    Indirect-to-direct transition of stimulated emission in AlxGa1−xAs (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 1102-1104 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The sensitivity of the threshold for stimulated emission on temperature is typically described by the T0 parameter of a heuristic exponential law. This T0 parameter has a value of about 80 K in AlxGa1−xAs heterostructures with a direct fundamental gap, while it is rather large (300 K) in indirect-gap AlxGa1−xAs. Samples with an AlAs mole fraction (here x=0.43 and 0.44) close to the direct-to-indirect crossover change the nature of their fundamental gap, and thus the dominant channel for stimulated emission, from indirect to direct with rising lattice temperature. This temperature-induced change in bandstructure is reflected in a drastic change of the T0 parameter. As a direct consequence of the differential T0 values, indirect-gap Al0.46Ga0.54As has a room-temperature threshold comparable to the standard laser material Al0.33Ga0.77As.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106357
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  • 7
    Electronic Resource
    Electronic Resource
    A study of polar CdTe (111) surfaces using angle-resolved x-ray photoelectron and Auger electron spectroscopy and low-energy electron diffraction (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 2583-2590 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and low-energy electron diffraction (LEED) have been used to study the polar (111)Cd and (111)Te surfaces of intrinsic CdTe crystals. Complementary information on surface composition, chemical state of the surface elements, and surface structure was obtained. The Auger parameters were used to identify the chemical states of elements on surfaces of semi-insulating undoped CdTe crystals which suffered from static charging effects. With this approach, we were able to determine that after chem-mechanical polishing, the Te-rich surface layer was mostly in the pure Te state. Only a trace amount of TeO2 was detectable. Sputtered and vacuum annealed (111) surfaces were found to be stoichiometric: both Cd and Te were in the chemical state of CdTe. Both (111) Cd and (111) Te surfaces showed sixfold symmetric LEED patterns. No evidence of surface reconstruction was found. Angle-resolved XPS showed no significant difference between 0° and 70° tilt on either the (111) Cd or (111) Te surfaces. Angle-resolved AES, however, showed significant differences between (111) Cd and (111) Te at 0° and 70° tilt, and the crystallographic polarity identified this way was consistent with results based on chemical etching and standard AES techniques, and with reported results of x-ray diffraction and transmission electron microscopy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.345488
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of surface treatments on bond strength of glass-infiltrated ceramic (2001)
    Oxford UK : Blackwell Science Ltd
    Journal of oral rehabilitation 28 (2001), S. 0 
    Details
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The purpose of this study was to evaluate the effects of various surface treatments on the bond strength at the In-Ceram/resin composite interface. Ninety-eight In-Ceram specimens were divided into seven groups and exposed to various surface treatments as follows: (A) control (B) saliva contamination (C) saliva contamination plus aluminum oxide sandblasting (D) glove powder contamination (E) glove powder contamination plus aluminum oxide sandblasting (F) rough aluminum oxide sandblasting and (G) excess glass infiltration. A resin composite cylinder was cemented to each In-Ceram specimen with Panavia 21 resin luting cement. Half of the cemented specimens in each group were stored in water for 24 h, and the other half were stored in water for 2 weeks and then were thermo-cycled for 2000 cycles. Shear bond strengths (SBS) of seven specimens in each subgroup were determined and analysed using analysis of variance (ANOVA) and Tukey HSD test as well as Student‘s t-test. Scanning electronic microscopy was used to identify the type of bond failure. Shear bond strength was significantly decreased by saliva and glove powder contaminations (P 〈 0·05). Sandblasting treatment did not improve the saliva-contaminated specimens. However, the glove powder plus sandblasting group showed no significant difference in SBS compared with the control group. There was no significant difference in SBS between the excess glass-infiltrating group and the control group. The SBS was significantly decreased by rough aluminum oxide sandblasting (P 〈 0·05). The SBS values of groups without thermocycling were significantly greater than those of groups with thermocycling (P 〈 0·05). There were no significant differences among SBS values of the seven groups with thermocycling. Combined cohesive and adhesive bond failures were seen in every group. Various surface treatments or contaminants may significantly influence the bond strength of In-Ceram restorative in clinical use.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2842.2001.00735.x
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  • 9
    Electronic Resource
    Electronic Resource
    Thin epitaxial gallium aluminum arsenide layers grown by multi-compartment liquid-phase epitaxy
    Amsterdam : Elsevier
    Journal of Crystal Growth 121 (1992), S. 566-570 
    Details
    ISSN: 0022-0248
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0022-0248(92)90563-X
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  • 10
    Electronic Resource
    Electronic Resource
    Effect of vibrational stirring on the quality of Bridgman-grown CdTe
    Amsterdam : Elsevier
    Journal of Crystal Growth 102 (1990), S. 807-813 
    Details
    ISSN: 0022-0248
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0022-0248(90)90846-D
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